Gelled foodstuff for aquatic animals

ABSTRACT

The subject of the invention is a gel-like feed for aquatic animals, especially fish, shrimps and invertebrates, in fresh and sea water, usable as replacement of frost feed for the nutrition of warm and cold water ornamental fish in an aquarium. An ornamental fish feed is preferred which contains 0.001-50% of gel former, 0.1-90% of natural feed and, depending upon the purpose of use, further additives, in the case of a water content of 20-99%. A feed is especially preferred which contains 0.1-10% of gel former, 1-20% of natural feed and, depending upon the purpose of use, further additives in the case of a water content of 50-99%.

The invention concerns an industrially producable feed for aquaticanimals in fresh and sea water, especially fish, shrimps andinvertebrates, also usable as replacement of frozen natural feed (frostfeed) for warm and cold water ornamental fish in the form of a viscousgel.

The feeding of frozen natural feed (e.g. saline crabs=Artemia; krill;water-fleas=Daphnia; stream flea crabs=Gammarus; sludge tubularworms=Tubifex; red midge larvae=Chironomus; white midgelarvae=Chaoborus; black midge larvae =Culex; zooplankton=Cyclops; fishroe; calf heart; menus=combination products) to warm and cold waterornamental fish is known. Specialised aquariarists often exclusivelyfeed living feed, FD (=freeze dried) natural feed and/or frost feed.However, the preponderant majority of aquariarists administer any feed(flakes, extrudates, tablets, pellets), in part in combination with theabove-mentioned types of feed.

The analysis of frost feed provides data for the chemical composition:the average water content or content of dry substance amounts to 90-95%and 5-10% respectively. Thus, frost feed is characterised by a very highcontent of water.

Feed animals in frozen state are sold in the form of blocks, sheets orcubes. For the storage of frost feed, not only in the case of the traderbut also in the case of the aquariarist, a freezer storage is necessary.For this form of feed conservation, a deep freezer or a freezercompartment in the refrigerator is necessary in which temperaturesclearly below 0° C. can be produced. The deep-frozen feed is eitherfirst thawed by the aquariarist and then fed or, however, is introducedin the frozen state into the aquarium water. Due to the usuallyrelatively high water temperature of about 20-30° C., the natural feedthaws rapidly and can be eaten by the ornamental fish. However, afterthe thawing the feed is to be given quickly since it decomposes rapidly.Feed once thawed must not be frozen again. In the refrigerator, deepfrozen feed can be kept 3-4 days, in the case of temperatures clearlybelow 0° C. it is storable for a maximum of one year.

Therefore, it is the task of the invention to make available anindustrially producable feed for aquatic animals, especially fish,shrimps and invertebrates, usable in fresh and sea water, which isusable in the aquarium especially for warm and cold water ornamentalfish as potential replacement for frost feed without thereby displayingthe described disadvantages of deep frozen feed.

Surprisingly, it has now been found that, by the use of gel formers,preferably a combination of several gel formers, and above-mentionednatural feeds alone or in combination, as well as possibly additionalnatural raw materials (e.g. Spirulina algae), vitamins, mineralmaterials, aroma materials, preservation agents and other additives, afeed can be produced industrially which is usable as replacement forfrost food and, at normal room temperature, is storable without problemsand thus possesses clearly improved handling properties as frost food.

Therefore, the subject of the invention is a feed for aquatic animals,especially fish, shrimps and invertebrates, in fresh and sea water,usable as replacement of frost feed for the nutrition of warm and coldwater ornamental fish in the aquarium in form of a viscous gel.

An ornamental fish feed is preferred which contains 0.001-50% of gelformer, 0.1-90% of natural feed and, depending upon the purpose of use,further additives, in the case of a water content of 20-99%. A feed isespecially preferred which contains 0.1-10% of gel former, 1-20% ofnatural feed and, depending on the purpose of use, further additives, inthe case of a water content of 50-99%.

The viscosity of gel-like feed of the invention is in a range of 1 to2×10⁶ mpa•s, preferably in the range of 1×10² to 1×10⁶ mpa•s andespecially preferred in the range of 1,5×10² to 5×10⁵ mpa•s.

Suitable gel formers can be synthetic, semisynthetic or of naturalorigin.

Synthetic gel formers are, for example, cellulose ethers, such as alkyl-and/or hydroxyalkyl-substituted cellulose ethers with 1 to 4 carbonatoms in the alkyl chain, preferably methylcellulose,hydroxyethylcellulose, hydroxypropylcellulose,hydroxyethylmethyl-cellulose, hydroxyethylethylcellulose,hydroxypropyl-methylcellulose or the like. HPMC is especially preferred.

Natural gel formers or semi-synthetic gel formers or ones obtained inbiotechnological ways are hydrocolloids of vegetable, animal orbacterial origin, such as e.g. polysaccharides, vegetable gums orcollagens. These are obtained from natural algae, natural vegetable seedgums, natural vegetable juices, natural fruit extracts, biosyntheticgums, biosynthetically modified starches or cellulose materials orexocellular polysaccharides. There are suitable, for example, pectins,alginates, carrageenan, agar agar, guar gum, gum arabic, tragacanth,Karaya gum, ghatti gum, locust bean flour, arabian, gellan,konjacmannan, galactomannan, funoran, sago, tara gum, xanthans, acetan,welan, rhamsan, furcelleran, succinoglycan, scleroglycan, schizophyllan,tamarind gum, curdlan, pullulan, dextran or gelatine. Especiallypreferred is agar agar.

The mentioned gel formers can be used alone or preferably in synergisticcombinations improving the acceptance and the properties of the feed.

For the improvement of the properties and, above all, of the acceptance,the feed mixtures according to the invention can additionally containsofteners or moisture retainers, such as e.g. glycerol, polyethyleneglycol, propylene glycol, glycine, sorbitol, mannitol, canesugar, maizesyrup, fructose, dioctyl sodium sulphosuccinate, triethyl citrate,tributyl citrate, 1,2-propylene glycol, mono-, di- or triacetates ofglycerol, acetamide, formamide or lactamide, namely, alone or insynergistic combinations.

For the improvement of the consistency and of the holding together ofthe feed mixture, additional chelate formers can be contained therein,such as e.g. ethylenediamine-tetraacetic acid, acetic acid, boric acid,citric acid, gluconic acid, lactic acid, phosphoric acid, tartaric acid,as well as salts of the said acids or metaphosphates,dihydroxyethylglycine, lecithin or beta-cyclodextrin or mixturesthereof.

The preferred gel-like feed of the invention is a complete substitute offrost feed. It contains preferably natural feed as complete animals orparts. Preferred kinds of natural feed are saline crabs (Artemia);krill; water-fleas (Daphnia); stream flea crabs (Gammarus); sludgetubular worms (Tubifex); red midge larvae (Chironomus); white midgelarvae (Chaoborus); black midge larvae (Culex); zooplankton (Cyclops);Bosmina; Mysis; shrimps; maggots; mealworms; fish roe; crab eggs; musselmeat; fish meat; cuttlefish or calf heart which are used alone or incombinations as whole animals and/or parts therof.

The recipe of the novel feed is composed of various components.Favourable for the consistency of the feed, as well as the holdingtogether of the particles are gel formers, e.g. agar agar, a gellingagent produced from marine algae belonging to the hydrocolloid group.Agar agar is a dried hydrophilic colloid substance of gigantic moleculeswhich have a linear, filament-formed construction and consist above allof galactose. For the production, some types of the red algae are used,namely, Gelidium and Gracellaria. The hydrocolloid is not soluble incold water but is practically completely soluble at higher temperatures.The melting point lies at about 90° C., the gel point at about 35-40°C., with formation of a strong, clear, thermoreversible gel which firstmelts again at temperatures above 85° C.

The gel-like feed according to the invention is expediently produced bymeans of an extruder from one or more natural types of feed and/orcommercially available feed mixtures, raw materials and one or moregelformers, as well as possibly usual vitamins, mineral, colouring,aroma, lure and preservation materials with addition of large amounts ofwater or, however, worked up by means of impeller-type mixers. Theforming, cooling and packaging takes place subsequently.

Preferably the feed is directly filled in ready to use form in jars,cans, bags, tubes or the like or packaged as cylindrically-shapedsticks. It can also be treated by further drying and thereafter furtherprocessed to feed forms like granulates, cubes, plates, flakes ortablets which, if necessary, have to be recondioned with water shortlybefore feeding. If natural feeds, such as e.g. midge larvae, Daphnias orplanktonic animals are worked up then it can be further worked up indry, fresh or thawed state with or without liquid.

As preservatian agents, there usually find use ethoxyquin, BHT, calciumpropionate, potassium sorbate, citric acid, lactic acid or salt (cookingor sea salt).

For lowering the pH value, there are also used commercially availablecomponents, such as e.g. lactic acid or hydrochloric acid.

The pieces of feed according to the invention are relatively large withregard to the mostly smaller ornamental fish. Therefore, the feedoffered cannot be eaten as a whole, on the contrary the fish bite smallpieces therefrom. It is a prerequisite that, by suitable choice of oneor more gel formers, under certain conditions in combination with othernutritional components, the consistency of the feed is so adjusted thatthe fish, because of the soft property, can bite off, without problems,mouth-sized pieces and subsequently swallow. A further possibilityconsists in the production and application of a feed, the gel formers ofwhich, because of their specific dissolving behaviour, dissolve whollyor partly in the water and thus liberate the nutritional components.

Examples for possible feed recipes:

Variant 1 Variant 2 gel former 1.5-5.5% 0.5-10%  preservation agent 0.1-12.4%  0.15-11.9%, natural feed 0.1-9%   0-3% aroma materials — 1-10% colorant —   -0.05% water 73-94% 70-90%

What is claimed is:
 1. A frost feed replacement for fresh and sea wateraquatic animals in the form of a gel, comprising a.) 0.001-50% of gelformer; b.) 0.1-90% of natural feed as complete animals; and c.) a watercontent of 50-99% by weight wherein the gel is formed at temperatureselevated enough for gel former to react with water, the gel formationoccurring prior to contact with the aquatic environment of the aquaticanimals and wherein the gel has a viscosity of 1 to 2×10⁶ mpa•s suchthat it resembles frozen natural feed sufficiently to act as replacementfor frozen natural feed.
 2. A feed according to claim 1, containing0.1-10% of gel former, 1-20% of natural feed and a water content of50-99% by weight.
 3. A feed according to claim 1, wherein the gel formeris selected from the group consisting of alkyl- and/orhydroxyalkyl-substituted cellulose ethers with 1 to 4 carbon atoms inthe alkyl chain, polysaccharides, vegetable gums, collagens or mixturesthereof.
 4. A feed according to claim 3, characterized in that thecellulose ether is selected from the group of methylcellulose,hydroxyethylcellulose, hydroxypropylcellulose,hydroxyethylmethylcellulose, hydroxyethylethylcellulose orhydroxypropylmethylcellulose.
 5. A feed according to claim 3,characterised in that the gel former is selected from the group ofpectins, alginates, carrageenan, agar agar, guar gum, gum arabic,tragacanth, Karaya gum, ghatti gum, locust bean flour, arabian, gellan,Konjacmannan, galactomannan, funoran, sago, tara gum, xanthans, acetan,welan, rhamsan, furcelleran, succinoglycan, scleroglycan, schizophyllan,tamarind gum, curdlan, pullulan, dextran or gelatine.
 6. A feedaccording to claim 1, further comprising a softener or moistureretainer.
 7. A feed according to claim 6, characterized in that glycerolis used as softener.
 8. A feed according to claim 1, characterized inthat it contains preservation agents.
 9. A feed according to claim 8,wherein the preservation agents are selected from the group consistingof ethoxyquin, BHT, calcium propionate, potassium sorbate, citric acid,lactic acid or salt.
 10. A feed according to claim 1, characterized inthat it contains additional natural raw materials.
 11. A feed accordingto claim 1, characterized in that it contains additionally vitamins,mineral, aroma, lure, colour and/or carotenoids.
 12. A process for theproduction of a feed according to claim 1, characterized in that one ormore natural types of feed and/or commercially available feed mixtures,raw materials are mixed with one or more gel formers, and water in anextruder at temperatures elevated enough to produce a reaction betweenthe gel former and water and subsequently, with cooling, the mixture isformed by means of an extruder to give cylinder-shaped sticks,granulates, cubes, plates, flakes or tablets of water content of from20-99% by weight and these filled into glasses, tins, blister packs or,directly after the extruder, packed and subsequently cooled.
 13. Aprocess for the production of a feed according to claim 1, characterizedin that one or more kinds of natural feed and/or commercially availablefeed mixtures, raw materials are mixed with one or more gel formers, andwater at temperatures elevated enough to produce a reaction between thegel former and water, the mixing by means of stirrers and homogenisationdevices and subsequently, with cooling, the mixture is formed to givecylinder-shaped sticks, granulates, cubes, plates, flakes or tablets ofwater content of from 20-99% by weight and these filled into glasses,tins, blister packs or packed directly and subsequently cooled.
 14. Afrost feed replacement for fresh and sea water aquatic animals in theform of a gel, comprising a.) 0.001-50% of gel former; b.) 0.1-90% ofnatural feed as complete animals or animal parts selected from the groupconsisting of saline crabs (Artemia); krill; water-fleas (Daphnia);stream flea crabs (Gammarus); sludge tubular worms (Tubifex); red midgelarvae (Chironomus); white midge larvae (Chaoborus); black midge larvae(Culex); zooplankton (Cyclops); Bosmina; Mysis; shrimps; maggots;mealworms; fish roe; crab eggs; mussel meat; fish meat; cuttlefishand/or calf heart alone or in combinations; and c.) a water content of50-99% by weight wherein the gel is formed at temperatures elevatedenough for gel former to react with water, the gel formation occurringprior to contact with the aquatic environment of the aquatic animals andwherein the gel has a viscosity of 1 to 2×10⁶ mpa.s such that itresembles frozen natural feed sufficiently to act as replacement forfrozen natural feed.